Oncological nuclear medicine: from antibody to PET

Department of Diagnostic Imaging has recently established in the Molecular Imaging Center of the National Institute of Radiological Sciences. The major aim of the department is to develop novel molecular imaging probes and to establish functional imaging methods of various cancers. The department consists of three sections; 1) biomolecule section (find out optimal biomolecule as the target of cancer imaging), 2) molecular diagnosis section (develop imaging method using specific molecular probe), and 3) clinical diagnosis section (applying molecular imaging modalities to cancer patients). In the present lecture, I would like to review my experiences in various aspects of cancer imaging using nuclear medicine procedures, which might be important in the research in the new department. The talk includes; 1) characteristics and limitations of cancer targeting with radiolabeled anti-cancer monoclonal antibodies and the attempts to overcome the limitations including pre-targeting strategy, 2 ) application of a newly synthesized polyamine (dendrimer) to the delivery and imaging of oligo-DNA and cancer treatment, 3) transfection of Na '/I - sym-porter gene to add iodide uptake mechanism to non-thyroid cancer cells for the wider application of radioiodine therapy, which is now also used as a promising reporter gene in gene therapy, and 4) basic and clinical study of PET metabolic imaging with fluorodeoxyglucose (FDG) and fluoro-thymidine (FLT) to evaluate the characteristics of various cancers. Although these modalities can not directly visualize molecular processes occurring in cancer cells, we can evaluate the imaging results with the insight of molecular biology, and the experiences of these modalities can be the bases for the future development of molecular imaging of malignant tumors. (author)